7.6 Carbon Cycle & Water cycle

Earth constantly recycles atoms & molecules so they can be used over & over again

Water cycle

  • energy from sun evaporates some water (from lakes / oceans / rivers / soil) into water vapour in the air

  • Accumulated water vapour condenses into clouds - which can then be blown from one region to another

  • Water falls back down to surface as liquid water (rain / precipitation)

  • Seeps into soil / flows into rivers / taken in by plants

  • Cycle repeats

Carbon cycle

Carbon split between 5 stores: in the air (CO2), in plants, in soil, in fossil fuels, in animals

  1. Photosynthesis by green plants takes in CO2

  2. Can be passed back out to atmosphere by respiration or passed on to animals that eat the plants (animals respire & pass on CO2)

  3. When organisms die - they are decayed by microorganisms (that live in warm, moist, aerobic conditions of soil) that break the organism into small pieces until all carbon is released as carbon dioxide during microbial respiration

  4. If animal decays anaerobically (without oxygen) then it will slowly convert into fossil fuels

  5. Fossil fuels burned by humans to produce carbon dioxide